Motorcycle dynamic exhaust system

ABSTRACT

The present invention provides a method of operating a dynamic exhaust system of a motorcycle engine. The method includes providing a valve in the exhaust system that is movable to direct exhaust gases between a first flow path through the exhaust system and a second flow path through the exhaust system. The method includes actuating the valve at a first speed to redirect exhaust gases from the first flow path to the second flow path and actuating the valve at a second speed greater than the first speed to redirect exhaust gases from the second flow path to the first flow path.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. patent application Ser. No.10/881,189, filed on Jun. 30, 2004, the entire contents of which areincorporated by reference.

BACKGROUND

This invention relates generally to motorcycles, and more particularlyto dynamic exhaust systems for motorcycles.

Various designs of motorcycle dynamic exhaust systems are known in theart. Typically, dynamic exhaust systems are utilized to alter theperformance of the motorcycle's engine and/or the noise emissions fromthe motorcycle's engine. In a conventional dynamic exhaust system for amotorcycle, a valve is positioned in a muffler to define a restrictiveflow path through the muffler, which may be utilized when it isdesirable to decrease the noise emissions of the engine, and a lessrestrictive flow path, which may be utilized when it is desirable toincrease the performance of the engine. The valve is typically moved todirect exhaust gases from the engine through either of the restrictiveor less restrictive flow paths. An actuator that is responsive to enginevacuum is commonly utilized to actuate the valve, such that when enginevacuum is high, the actuator actuates the valve to direct the exhaustgases through the restrictive flow path of the muffler to quiet theengine. Also, when the engine vacuum is low, the actuator actuates thevalve to direct the exhaust gases through the less restrictive flow pathof the muffler to increase the performance of the engine.

SUMMARY

The present invention provides a method of operating a dynamic exhaustsystem of a motorcycle engine. The method includes providing a valve inthe exhaust system that is movable to direct exhaust gases between afirst flow path through the exhaust system and a second flow paththrough the exhaust system. The method includes actuating the valve at afirst speed to redirect exhaust gases from the first flow path to thesecond flow path and actuating the valve at a second speed greater thanthe first speed to redirect exhaust gases from the second flow path tothe first flow path.

The method includes, in another aspect, actuating the valve in theexhaust system in a crossover region of first and second torquecharacteristics of the first and second flow paths, respectively.

The present invention provides, in yet another aspect, a motorcycleincluding a valve and an actuator supported by an airbox. The actuatoris operatively coupled to the valve to move the valve between a firstposition, in which exhaust gases are directed along the first flow path,and a second position, in which exhaust gases are directed along thesecond flow path.

Other features and aspects of the present invention will become apparentto those skilled in the art upon review of the following detaileddescription, claims and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, wherein like reference numerals indicate like parts:

FIG. 1 is a cross-sectional view of a first construction of a dynamicexhaust system embodying the present invention, illustrating exhaustgases flowing through a first flow path of the exhaust system.

FIG. 2 is a cross-sectional view of the dynamic exhaust system of FIG.1, illustrating exhaust gases flowing through a second flow path of theexhaust system.

FIG. 3 is a partial cross-sectional view of a second construction of adynamic exhaust system embodying the present invention, illustratingexhaust gases flowing through a first flow path of the exhaust system.

FIG. 4 is a partial cross-sectional view of the dynamic exhaust systemof FIG. 3, illustrating exhaust gases flowing through a second flow pathof the exhaust system.

FIG. 5 is a cutaway perspective view of a third construction of adynamic exhaust system embodying the present invention, illustratingexhaust gases flowing through a first flow path of the exhaust system.

FIG. 6 is a cutaway perspective view of the dynamic exhaust system ofFIG. 5, illustrating exhaust gases flowing through a second flow path ofthe exhaust system.

FIG. 7 is a perspective view of a motorcycle including the dynamicexhaust system of FIGS. 5 and 6, illustrating an actuator positionedremotely from the exhaust system.

FIG. 8 is a graph illustrating a first torque characteristic of amotorcycle engine representative of exhaust gases flowing through thefirst flow path of the exhaust system of FIGS. 5 and 6, and a secondtorque characteristic of the motorcycle engine representative of exhaustgases flowing through the second flow path of the exhaust system ofFIGS. 5 and 6.

Before any features of the invention are explained in detail, it is tobe understood that the invention is not limited in its application tothe details of construction and the arrangements of the components setforth in the following description or illustrated in the drawings. Theinvention is capable of other embodiments and of being practiced orbeing carried out in various ways. Also, it is understood that thephraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including”, “having”, and “comprising” and variations thereof herein ismeant to encompass the items listed thereafter and equivalents thereofas well as additional items. The use of letters to identify elements ofa method or process is simply for identification and is not meant toindicate that the elements should be performed in a particular order.

DETAILED DESCRIPTION

FIGS. 1 and 2 illustrate a first construction of a motorcycle dynamicexhaust system 10 embodying the present invention. The exhaust system 10includes a muffler 14 coupled to an exhaust pipe 18 in a conventionalmanner. Although not shown, the exhaust system 10 may incorporate asecond exhaust pipe and a second muffler.

The muffler 14 incorporates a valve assembly 22 a to direct the flow ofexhaust gases through the muffler 14. In the illustrated construction,the valve assembly 22 a includes a valve housing 26 defining a centralpassageway 30. A shaft 34 is rotatably supported by the valve housing26, and a butterfly valve 38 is coupled to the shaft 34. The butterflyvalve 38 is positioned in the central passageway 30 to selectivelyrestrict the flow of exhaust gases through the passageway 30, asdiscussed in more detail below. The shaft 34 extends through an outershell 42 of the muffler 14, and a quadrant or a lever 46 is coupled tothe shaft 34 to receive a cable 50 for pivoting or rotating the shaft 34and the butterfly valve 38.

The muffler 14 also includes an inlet tube 54 coupled to the valvehousing 26 at an inlet end of the valve housing 26, and an outlet tube58 coupled to the valve housing 26 at an outlet end of the valve housing26. The inlet tube 54 is supported in the outer shell 42 of the muffler14 by a tube support member 62. The muffler 14 further includes acatalyst 66 located within a catalyst tube 70, which is coupled to theinlet tube 54 via a transition sleeve 74. A first sleeve 78 surroundsthe inlet tube 54 and is coupled between the tube support member 62 andthe transition sleeve 74. A plug 82 is positioned within the inlet tube54 such that unobstructed flow of exhaust gases through the entirelength of the inlet tube 54 is restricted.

With continued reference to FIGS. 1 and 2, the muffler 14 includes asecond sleeve 86 surrounding the outlet tube 58, such that opposite endsof the second sleeve 86 are pinched into contact with the outer surfaceof the outlet tube 58. The muffler 14 also includes a third sleeve 90surrounding the second sleeve 86, with one end of the third sleeve 90being coupled to the tube support member 62 and the opposite end beingin abutting contact with the outer shell 42.

As a result of the above-identified internal components of the muffler14, the muffler 14 generally defines a plurality of chambers throughwhich exhaust gases may flow. More particularly, the space bounded bythe catalyst tube 70, the transition sleeve 74, and a portion of theinlet tube 54 upstream of the plug 82 defines a first chamber 94, whilethe space bounded by the first sleeve 78, the inlet tube 54, thetransition sleeve 74, and the tube support member 62 defines a secondchamber 98. In addition, the space bounded by a portion of the inlettube 54 downstream of the plug 82 and the closed butterfly valve 38defines a third chamber 102, and the space bounded between the secondsleeve 86, and the third sleeve 90, and the tube support member 62defines a fourth chamber 106. Further, the space bounded by the secondsleeve 86 and the outlet tube 58 defines a fifth chamber 110, while thespace bounded by the closed butterfly valve 38 and the outlet tube 58defines a sixth chamber 114.

With reference to FIG. 1, a first flow path of exhaust gases is shownthrough the muffler 14 by a sequence of arrows. The butterfly valve 38is shown pivoted to an open position, in which unobstructed flow ofexhaust gases is allowed through the passageway 30 in the valve housing26. More particularly, exhaust gases exiting the exhaust pipe 18 enterthe first chamber 94 of the muffler 14 and encounter the plug 82, whichredirects the ehxuast gases into the second chamber 98 via a pluralityof first apertures 118 formed in the inlet tube 54. The exhaust gasesare then directed into the third chamber 102 via a plurality of secondapertures 122 formed in the inlet tube 54. From the third chamber 102,the exhaust gases may pass unobstructed through the passageway 30 of thevalve housing 26 and enter the sixth chamber 114, thereby bypassing thefourth and fifth chambers 106, 110 of the muffler 14. From the sixthchamber 114, the exhaust gases may exit the muffler 14.

With reference to FIG. 2, a second flow path of exhaust gases is shownthrough the muffler 14 by a sequence of arrows. The butterfly valve 38is shown pivoted to a closed position, in which exhaust gases are notallowed to flow through the passageway 30 in the valve housing 26. Moreparticularly, exhaust gases pass through the first, second, and thirdchambers 94, 98, 102 as described above with reference to FIG. 1.However, since the butterfly valve 38 is closed, exhaust gases in thethird chamber 102 are directed into the fourth chamber 106 via theplurality of second apertures 122. From the fourth chamber 106, theexhaust gases are directed into the fifth chamber 110 via a plurality ofthird apertures 126 formed in the second sleeve 86. Further, the exhaustgases in the fifth chamber 110 are directed into the sixth chamber 114via a plurality of fourth apertures 130 formed in the outlet tube 58.From the sixth chamber 144, the exhaust gases may exit the muffler 14.

FIGS. 3 and 4 illustrate a second construction of a motorcycle dynamicexhaust system 134 of the present invention. The exhaust system 134 is adual exhaust system 134 including a first muffler 138 and a secondmuffler 142. In the illustrated construction, the first muffler 138 is aconventional multi-chamber muffler 138 while the second muffler 142 is ahigh-performance single chamber muffler 142. However, alternateconstructions of the exhaust system 134 may utilize two high-performancesingle chamber mufflers 142 or two conventional multi-chamber mufflers138.

In the illustrated construction, a valve 22 b is positioned in theexhaust system 134 upstream of the second muffler 142. The valve 22 b issubstantially similar to the valve 22 a shown in FIGS. 1 and 2. As shownin FIGS, 3 and 4, the exhaust system 134 also includes a first exhaustpipe 146 coupled to the first muffler 138, and a second exhaust pipe 150coupled to and merged with the first exhaust pipe 146. The first andsecond exhaust pipes 146, 150 may be connected to respective ehxuastports of a motorcycle engine (e.g., a V-twin engine, not shown) toreceive exhaust gases. The exhaust system 134 further includes a thirdexhaust pipe 154 coupled to and merged with the second exhaust pipe 150.The third exhaust pipe 154 is also coupled to the valve 22 b, which, inturn, is coupled to the second muffler 142.

With reference to FIG. 3, a first flow path of exhaust gases is shownthrough the exhaust system 134 by a sequence of arrows. The butterflyvalve 38 is shown pivoted to an open position, in which unobstructedflow of exhaust gases is allowed through the valve 22 b. Moreparticularly, exhaust gases may be redirected from the second exhaustpipe 150 to the third exhaust pipe 154, thereby utilizing both of thefirst and second mufflers 138, 142.

With reference to FIG. 4, a second flow path of exhaust gases is shownthrough the exhaust system 134 by a sequence of arrows. The butterflyvalve 38 is shown pivoted to a closed position, in which exhaust gasesare not allowed to flow through the valve 22 b. More particularly,exhaust gases may not be redirected from the second exhaust pipe 150 tothe second muffler 142, thereby only utilizing the first muffler 138 inthe exhaust system 134.

FIGS. 5 and 6 illustrate a third construction of a motorcycle dynamicexhaust system 158 of the present invention. The exhaust system 158includes a muffler 162 coupled to an exhaust pipe (not shown) in aconventional manner. Although not shown, the motorcycle may include adual exhaust system utilizing a second exhaust pipe and a secondmuffler.

Like the muffler 14 of FIGS. 1 and 2, the muffler 162 incorporates avalve 22 c therein to direct the flow of exhaust gases through themuffler 162. The valve 22 c is substantially similar to the valve 22 ashown in FIGS. 1 and 2. As shown in FIGS. 5 and 6, the valve 22 c iscoupled to a first or inlet tube 166 of the muffler 162. The inlet tube166 is supported by a first wall 170 and a second wall 174, which dividethe interior space of the muffler 162 as bounded by an outer shell 178into a first chamber 182, a second chamber 186, and a third chamber 190.The muffler 162 also includes a second or connecting tube 194 supportedby the first and second walls 170, 174 that communicates the first andthird chambers 182, 190. Further, the muffler 162 includes a third oroutlet tube 198 supported by the first and second walls 170, 174 thatcommunicates the third chamber 190 with the atmosphere.

With reference to FIG. 5, a first flow path of exhaust gases is shownthrough the exhaust system 158 by a sequence of arrows. The butterflyvalve 38 is shown pivoted to an open position, in which unobstructedflow of exhaust gases is allowed through the valve 22 c. As such,exhaust gases from the inlet tube 166 are allowed to discharge directlyinto the third chamber 190 (i.e., bypassing the first chamber 182),where the exhaust gases may flow through the outlet tube 198 and exitthe muffler 162.

With reference to FIG. 6, a second flow path of exhaust gases is shownthrough the exhaust system 158 by a sequence of arrows. The butterflyvalve 38 is shown pivoted to a closed position, in which exhaust gasesare not allowed to flow through the valve 22 c. As such, exhaust gasesare directed to the first chamber 182 via the inlet tube 166, and to thethird chamber 190 via the connecting tube 194. From the third chamber190, the exhaust gases may flow through the outlet tube 198 and exit themuffler 162.

With reference to FIG. 7, a motorcycle 202 is shown that incorporatesthe dynamic exhaust system 158 of FIGS. 5 and 6. FIG. 7 schematicallyillustrates the valve 22 c positioned toward the bottom of themotorcycle 202. However, in a motorcycle configured to receive theexhaust systems 10, 134, the valves 22 a, 22 b may be positionedrelative to the motorcycle in a location appropriate with theconfiguration of the respective exhaust systems 10, 134. As such, theposition of the valve 22 c as shown in FIG. 7 is for illustrativepurposes only.

The illustrated motorcycle 202 is configured with an airbox (thelocation of which is designated by reference numeral 206) in a locationon the motorcycle 202 typically associated with a fuel tank. The airbox206 houses conventional air intake components (e.g., an air filter, notshown) for the engine. The airbox 206 is also configured to receive anactuator 210 for opening and closing the valve 22 c of the exhaustsystem 158. The actuator 210 may be mounted on top of the airbox 206 andprotected by a cover (not shown) covering the airbox 206.

The actuator 210 may be a conventional servo-motor having a quadrant orlever 214 for pulling or releasing the cable 50. The cable 50 isschematically illustrated as extending from the upper portion of themotorcycle 202 to the bottom portion of the motorcycle 202. However, thecable 50 may extend in any direction on the motorcycle 202 depending onthe location of the valve 22 c in the exhaust system 158. The cable 50may also be substantially hidden from view by routing the cable 50through frame members of the motorcycle 202 and/or hidden from viewbehind one or more fairings or body panels of the motorcycle 202.

The actuator 210 is electrically connected to an engine control unit 218(“ECU”) of the motorcycle 202. In addition to controlling otherfunctions of the motorcycle 202 (e.g., fuel injection, engine timing,etc.), the ECU 218 is configured to control operation of the actuator210. In addition, a second cable may be utilized to actuate a secondvalve.

Any of the dynamic exhaust systems 10, 134, 158 of FIGS. 1-6 may beutilized to alter the performance of the motorcycle's engine and/oralter the noise emission characteristics of the motorcycle's engine.With reference to FIG. 8, the engine's torque output is shown as afunction of engine speed (measured in revolutions per minute, or RPM).More particularly, curve A illustrates the engine's torque output whenthe exhaust gases are routed through the first flow path of the exhaustsystem 158, in which the valve 22 c is opened. Likewise, curve Billustrates the engine's torque output when the exhaust gases are routedthrough the second flow path of the exhaust system 158, in which thevalve 22 c is closed.

As shown in FIG. 8, the engine's torque output may be increased byopening the valve 22 c during low engine speeds and during high enginespeeds. However, maintaining the valve 22 c open during mid-range enginespeeds may also cause a decrease in torque output compared to theengine's output when the valve 22 c is closed. Such a decrease in torqueoutput may be caused by reversion of the exhaust gases in the exhaustsystem 158.

The engine exhibits different operating characteristics, or “torquecharacteristics,” depending on the position (e.g., open or closed) ofthe valve 22 c. For example, when the valve 22 c is in an open position,the engine may exhibit a first torque characteristic defined by curve A.Likewise, when the valve is in a closed position, the engine may exhibita second torque characteristic defined by curve B. Selective actuationof the valve 22 c between open and closed positions may allow the engineto exhibit a third torque characteristic defined by curve C that takesadvantage of the increase in torque output provided by the firstoperating characteristic during low engine speeds and high enginespeeds, while also taking advantage of the torque output provided by thesecond operating characteristic during mid-range engine speeds to reducethe effects of the above-described reversion phenomena.

More particularly, for the engine to exhibit the third torquecharacteristic and follow curve C, the valve 22 c is selectivelycontrolled according to engine speed to cause the engine to switch ortransition between exhibiting the first torque characteristic andexhibiting the second torque characteristic. For example, the valve 22 cmay be actuated from an open position to a closed position in a firstcrossover region, designated R1 in FIG. 8. The first crossover region R1may be centered about a first intersection or crossover point(designated P1) of curve A and curve B. Crossover point P1 correlateswith the engine speed at which the engine outputs substantially the sameamount of torque whether it is exhibiting the first torquecharacteristic or the second torque characteristic. As shown in FIG. 8,crossover point P1 occurs at about 3800 RPM, and the crossover region R1may extend between about 3600 RPM and about 4000 RPM. However,differently-configured engines may exhibit different torquecharacteristics than those defined by curve A and curve B. As such,crossover point P1 may occur at a higher or a lower engine speed than3800 RPM, and the crossover region R1 may be wider (i.e., encompass agreater range of engine speeds) or more narrow) i.e., encompass asmaller rang of engine speeds) than that illustrated in FIG. 8.

For the engine to continue exhibiting the third torque characteristicand following curve C, the valve 22 c is actuated from the closedposition back to the open position in a second crossover region,designated R1 in FIG. 8. The second crossover region R2 may be centeredabout a second intersection or crossover point (designated P2) of curveA and curve B. As shown in FIG. 8, crossover point P2 occurs at about5300 RPM, and the crossover region R2 shown in FIG. 8, crossover pointP2 occurs at about 5300 RPM, and the crossover region R2 may extendbetween about 5100 RPM and about 5500 RPM. However,differently-configured engines may exhibit different torquecharacteristics than those defined by curve A and curve B. As such,crossover point P2 may occur at a higher or a lower engine speed than5100 RPM, and the crossover region R2 may be wider (i.e., encompass agreater range of engine speeds) or more narrow (i.e., encompass asmaller range of engine speeds) than that illustrated in FIG. 8.

More particularly, the ECU 218 may be configured to trigger the actuator210, which in turn may actuate the valve 22 c, when the engine speedreaches the crossover points P1, P2 in the respective crossover regionsR1, R2. However, with respect to the crossover region R1, the ECU 218may trigger the actuator 210 at an engine speed within the crossoverregion R1 but at a lower speed or a higher speed than the crossoverpoint P1. Likewise, with respect to the crossover region R2, the ECU 218may trigger the actuator 210 at an engine speed within the crossoverregion R2 but at a lower speed or a higher speed than the crossoverpoint P2.

The ECU 218 may also trigger the actuator 210 slightly before the enginespeed reaches the crossover point P1, or slightly before the enginespeed reaches the crossover point P2 to take into account the mechanicallag associated with the actuator 210, cable 50, and valve 22 c. Inaddition, the ECU 218 may be configured to automatically make slightercorrections to the engine speed when the valve 22 c is actuated basedupon input received by the ECU 218 from various engine or motorcyclesensors. Further, one or more conditions may need to be satisfied inorder for the ECU 218 to trigger the actuator 210. For example, acondition that the engine must be operating at 75% of full throttle ormore may need to be satisfied in order for the ECU 218 to trigger theactuator 210.

The ECU 218 may also be configured to trigger the actuator 210, and thusthe valve 22 c, according to the speed of the motorcycle 202. It may bedesirable to trigger the actuator 210 according to the speed of themotorcycle 202 to alter the noise emission characteristics of theengine. For example, it may be desirable to operate the engine below apre-determined sound level during mid-range cruising speeds (e.g.,between 10 miles per hour and 50 miles per hour, or MPH). As a result,the ECU 218 may be configured to actuate the valve 22 c from the openposition to the closed position at about 10 MPH. In the closed position,the valve 22 c directs exhaust gases along a second flow path longerthan the first flow path to provide additional muffling of the soundpulses of the exhaust gases. At about 50 MPH, the ECU 218 may beconfigured to actuate the valve 22 c back to the open position from theclosed position. In the open position, the valve 22 c directs exhaustgases along the first flow path to decrease the amount of muffling ofthe sound pulses of the exhaust gases. The ECU 218 may also beconfigured to trigger the actuator 210 at other motorcycle speedsdepending on the desired sound levels or noise emission characteristicsof the engine.

Various aspects of the invention are set forth in the following claims.

1. A method of operating a dynamic exhaust system of a motorcycle engine, the method comprising: directing exhaust gases along a first flow path through the exhaust system to operate the engine at a first torque characteristic; actuating a valve in the exhaust system in a crossover region of the first torque characteristic and a second torque characteristic; and redirecting the exhaust gases from the first flow path to a second flow path through the exhaust system to operate the engine at the second torque characteristic.
 2. The method of claim 1, further comprising: actuating the valve in a second crossover region of the first torque characteristic and the second torque characteristic; and redirecting the exhaust gases from the second flow path to the first flow path to operate the engine at the first torque characteristic.
 3. The method of claim 1, wherein actuating the valve includes one of opening and closing the valve.
 4. The method of claim 1, wherein actuating the valve occurs when the engine is operating at least about 75 percent of full throttle.
 5. The method of claim 1, further comprising triggering an actuator to actuate the valve.
 6. The method of claim 5, wherein an engine control unit selectively triggers the actuator.
 7. The method of claim 1, wherein the crossover region is a range of engine speeds over which the first torque characteristic and the second torque characteristic are substantially equal.
 8. The method of claim 7, further comprising monitoring the engine speed with an engine control unit, wherein the valve is selectively actuated by the engine control unit.
 9. A motorcycle comprising: an exhaust system defining a first flow path and a second flow path; a valve positioned in the exhaust system, the valve operable to direct exhaust gases between the first flow path and the second flow path; an airbox positioned remotely from the exhaust system; and an actuator supported by the airbox and operatively coupled to the valve to move the valve between a first position, in which exhaust gases are directed along the first flow path, and a second position, in which exhaust gases are directed along the second flow path.
 10. The motorcycle of claim 9, further comprising a cable operatively coupling the actuator and the valve.
 11. The motorcycle of claim 8, further comprising an engine control unit adapted to trigger the actuator to move the valve between the first and second positions.
 12. The motorcycle of claim 11, further comprising an engine operable over a range of engine speeds, the engine exhibiting a first torque characteristic when exhaust gases are directed through the first flow path, the engine further exhibiting a second torque characteristic when exhaust gases are directed through the second flow path.
 13. The motorcycle of claim 12, wherein the engine control unit is configured to selectively trigger the actuator based on engine speed.
 14. The motorcycle of claim 13, wherein the engine control unit is configured to selectively trigger the actuator at an engine speed within a crossover region, in which the first torque characteristic is substantially equal to the second torque characteristic.
 15. The motorcycle of claim 9, wherein the exhaust system includes a muffler, and wherein the valve is located inside of the muffler.
 16. The motorcycle of claim 9, wherein the exhaust system includes a first muffler and a second muffler, wherein the valve directs exhaust gases through the first muffler along the first flow path, and wherein the valve substantially prevents exhaust gases from entering the first muffler along the second flow path. 